Process for manufacturing hydrocarbons

ABSTRACT

A catalytic process, employing a novel catalyst, for converting lower monohydric alcohols and their ethers, especially methanol and dimethyl ether, to a hydrocarbon mixture mostly ethylene, propylene and mononuclear aromatics. The novel catalyst is a composite of antimony oxide and a crystalline aluminosilicate zeolite such as ZSM-5.

FIELD OF THE INVENTION

This invention is concerned with the manufacture of hydrocarbons fromlower alcohols or their ethers. It is particularly concerned with thecatalytic conversion of such alcohols and ethers to hydrocarbon mixturesrich in ethylene. In another aspect, this invention is concerned with anovel catalyst especially effective for the conversion of lower alcoholsto ethylene and aromatic hydrocarbons.

DESCRIPTION OF PRIOR ART

A remarkable growth in the production of synthetic fibers, plastics andrubber has taken place in recent decades. This growth, to a very largeextent, has been supported and encouraged by an expanding supply ofinexpensive petrochemical raw materials such as ethylene, benzene,toluene, and xylenes. Side by side with this remarkable development,there has been an increasing demand for aromatic hydrocarbons for use ashigh octane gasoline components. Environmental factors which limit thelead content of gasoline are likely to aggravate the need for aromatics.

Burgeoning demand for olefins, particularly ethylene, and for aromatichydrocarbons, has of course led to periods of shortage, either due toshort supply of suitable feedstocks or to limited processing capacity.In any case, it would appear desirable to provide efficient means forconverting raw materials other than petroleum to olefins and aromatichydrocarbons.

Copending application Ser. No. 508,308, filed Sept. 23, 1974,(attorney's docket number Case 8487) discloses a catalyst comprising acrystalline aluminosilicate zeolite having a silica to alumina ratio ofat least about 12, a constraint index of about 1 to 12, and containingphosphorus incorporated with the crystal structure thereof in an amountof at least about 0.78 percent by weight and discloses the conversion ofaliphatic compounds, particularly hydrocarbons, both paraffins andolefins, by contact with the catalyst.

Copending application Ser. No. 508,307 filed Sept. 23, 1974, now U.S.Pat. No. 3,911,041, describes the conversion of methanol and of dimethylether to hydrocarbons when contacted with phosphorous-modified ZSM-5type catalyst.

Copending application Ser. No. 508,306, filed Sept. 23, 1974, now U.S.Pat. No. 3,906,054, discloses a process for the alkylation of olefinsemploying, as a catalyst, a crystalline aluminosilicate zeolite having asilica to alumina ratio of at least about 12, a constraint index ofabout 1 to 12, and containing phosphorus incorporated with the crystalstructure thereof in an amount of at least about 0.78 percent by weight.

Copending applications Ser. Nos. 387,222; 387,223; and 387,224, filedAug. 9, 1973, now U.S. Pat. Nos. 3,894,106, 3,894,107 and 3,907,915,respectively, disclose the conversion of alcohols and/or ethers and/orcarbonyls to higher carbon number hydrocarbons by contact with acatalyst comprising a crystalline aluminosilicate zeolite having asilica to alumina ratio of at least about 12 and a constraint index ofabout 1 to 12.

The conversion of methanol and dimethyl ether to hydrocarbons isdescribed in copending U.S. Patent Application Ser. No. 508,307, filedSept. 23, 1974.

A process for preparing attrition-resistant solid catalysts containingantimony oxide is described in U.S. Pat. No. 3,686,138, issued Aug. 22,1972.

BRIEF SUMMARY OF THE INVENTION

In the present invention, lower monohydric alcohols having up to fourcarbon atoms, their ether derivatives, or mixtures of any of these areconverted by contact at elevated temperatures with a novel catalyst,described below, to form hydrocarbon mixtures rich in light olefins,especially ethylene, and aromatic hydrocarbons. The novel catalystutilized in this invention is a composite of antimony oxide and a porousinorganic oxide preferably of the crystalline aluminosilicate zeolitetype as hereinafter described.

The alcohols may be manufactured from synthesis gas, i.e., a mixture ofCO and H₂, from coal, or they may be produced by fermentation, or theymay be manufactured from petroleum fraction in excess supply. Thearomatic hydrocarbons produced may be used to blend with gasoline, orthey may be separated and used as petrochemicals and as solvents. Thus,in one aspect, the present invention provides a novel means forproducing hydrocarbon petrochemicals and fuels.

PREFERRED EMBODIMENTS

Any composition consisting essentially of one or more compounds havingthe empirical formula [ (CH₂)n(CH₂)m ]H₂ O wherein n = 1 to 4 and m = 0to 4 may be used as feed to the process of this invention. Thus,methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol andisobutanol may be used either alone or in admixture with one another, orin admixture with the above alcohols. Likewise, mixed ethers derivedfrom these alcohols, such as methyl-ethyl ether, may be likewise used.It will be noted that all of the compounds indicated have the empiricalformula above described. Particularly preferred feeds are methanol,dimethyl ether and mixtures thereof.

The preferred catalysts of this invention comprise composites ofantimony oxide and a crystalline aluminosilicate zeolite more fullydescribed below. The ratio of antimony oxide to crystallinealuminosilicate zeolite may be from about 0.01 to about 0.50, andpreferably from about 0.03 to about 0.30. The ratio in all cases is byweight of Sb₂ O₃ to dry zeolite. The antimony oxide may be present asSb₂ O₃, Sb₂ O₄, Sb₂ O₅ or mixtures thereof with or without metallicantimony or other antimony compounds being present. In all instances,regardless of the particular state of oxidation of the antimony, itscontent vis a vis the zeolite is computed as if it were present as Sb₂O₃.

The catalysts of this invention may be a physical mixture of an antimonycompound, preferably an oxide such as Sb₂ O₃, Sb₂ O₄, or Sb₂ O₅, withthe zeolite powder; or, the product formed by impregnation of thezeolite powder or pellets with one or more organic or inorganic antimonycompound; or the product formed by any known catalyst preparationprocedure that results in an intimate mixture. Antimony derivativeswhich may be used include: the hydrides SbH₃ ; the halides MX₃, MX₅ (M =Sb, X = F, Cl, Br, I); organic alkyl and aryl stibines and their oxidesR₃ Sb, R₅ Sb, R_(x) Sb=O (R=alkyl or aryl); halogen derivatives RSbX₂,R₂ SbX, RSbX₄, R₂ SbX₃, R₃ SbX₂, R₄ SbX; the acids H₃ SbO₃, HSbO₂,HSb(OH)₆ ; organic acids such as RSbO(OH)₂, R₂ SbO . OH, all with R andX defined as above noted. Also included are organic ethers such as R₂SbOSbR₂ ; esters and alcoholates such as Sb(OOCH₃)₃, Sb(OC₄ H₉)₃, Sb(OC₂H₅)₃, Sb(OCH₃)₃ ; and antimonyl salts as (SbO)SO₄, (SbO)NO₃, K(SbO)C₄ H₄O₆, NaSbO₂ . 3H₂ O. Binders such as clays, silica, or other inorganicoxides may be used. When such are used, the total catalyst compositionshould preferably contain at least 50 percent by weight of crystallinealuminosilicate zeolite. When the catalyst composition has the desiredphysical form, it is dried and then calcined at a temperature of about200°C to about 600°C, preferably in an oxidizing atmosphere such as air.In some cases, calcining in a reducing atmosphere may be foundpreferable, in which case the calcining temperature should not exceedabout 550°C.

The catalysts referred to herein utilize members of a special class ofzeolites exhibiting some unusual properties. These zeolites bythemselves induce profound transformations of aliphatic hydrocarbons toaromatic hydrocarbons in commercially desirable yields and are generallyhighly effective in alkylation, isomerization, disproportionation andother reactions involving aromatic hydrocarbons. Although they haveunusually low alumina contents, i.e., high silica to alumina ratios,they are very active even with silica to alumina ratios exceeding 30.This activity is surprising since catalytic activity of zeolites isgenerally attributed to framework aluminum atoms and cations associatedwith these aluminum atoms. These zeolites retain their crystallinity forlong periods in spite of the presence of steam even at high temperatureswhich induce irreversible collapse of the crystal framework of otherzeolites, e.g. of the X and A type. Furthermore, carbonaceous deposits,when formed, may be removed by burning at higher than usual temperaturesto restore activity. In many environments the zeolites of this classexhibit very low coke forming capability, conducive to very long timeson stream between burning regenerations.

An important characteristic of the crystal structure of this class ofzeolites is that it provides constrained access to, and egress from, theintra-crystalline free space by virtue of having a pore dimensiongreater than about 5 Angstroms and pore windows of about a size such aswould be provided by 10-membered rings of oxygen atoms. It is to beunderstood, of course, that these rings are those formed by the regulardisposition of the tetrahedra making up the anionic framework of thecrystalline aluminosilicate, the oxygen atoms themselves being bonded tothe silicon or aluminum atoms at the centers of the tetrahedra. Briefly,the preferred zeolites useful in this invention possess, in combination:a silica to alumina ratio of at least about 12; and a structureproviding constrained access to the crystalline free space.

The silica to alumina ratio referred to may be determined byconventional analysis. This ratio is meant to represent, as closely aspossible, the ratio in the rigid anionic framework of the zeolitecrystal and to exclude aluminum in the binder or in cationic or otherform within the channels. Although zeolites with a silica to aluminaratio of at least 12 are useful, it is preferred to use zeolites havinghigher ratios of at least about 30. Such zeolites, after activation,acquire an intracrystalline sorption capacity for normal hexane which isgreater than that for water, i.e., they exhibit "hydrophobic"properties. It is believed that this hydrophobic character isadvantageous in the present invention.

The zeolites useful as catalysts in this invention freely sorb normalhexane and have a pore dimension greater than about 5 Angstroms. Inaddition, their structure must provide constrained access to some largermolecules. It is sometimes possible to judge from a known crystalstructure whether such constrained access exists. For example, if theonly pore windows in a crystal are formed by 8-membered rings of oxygenatoms, then access by molecules of larger cross-section than normalhexane is substantially excluded and the zeolite is not of the desiredtype. zeolites with windows of 10-membered rings are preferred, althoughexcessive puckering or pore blockage may render these zeolitessubstantially ineffective. Zeolites with windows of twelve-memberedrings do not generally appear to offer sufficient constraint to producethe advantageous conversions desired in the instant invention, althoughstructures can be conceived, due to pore blockage or other cause, thatmay be operative.

Rather than attempt to judge from crystal structure whether or not azeolite possesses the necessary constrained access, a simpledetermination of the "constraint index" may be made by continouslypassing a mixture of equal weight of normal hexane and 3-methylpentaneover a small sample, approximately 1 gram or less, of zeolite atatmospheric pressure according to the following procedure. A sample ofthe zeolite, in the form of pellets or extrudate, is crushed to aparticle size about that of coarse sand and mounted in a glass tube.Prior to testing, the zeolite is treated with a stream of air at 1,000°Ffor at least 15 minutes. The zeolite is then flushed with helium and thetemperature adjusted between 550°F and 950°F to give an overallconversion between 10% and 60%. The mixture of hydrocarbons is passed at1 liquid hourly space velocity (i.e., 1 volume of liquid hydrocarbon pervolume of catalyst per hour) over the zeolite with a helium dilution togive a helium to total hydrocarbon mole ratio of 4:1. After 20 minuteson stream, a sample of the effluent is taken and analyzed, mostconveniently by gas chromatography, to determine the fraction remainingunchanged for each of the two hydrocarbons.

The "constraint index" is calculated as follows: ##EQU1##

The constraint index approximates the ratio of the cracking rateconstants for the two hydrocarbons. Catalysts suitable for the presentinvention are those which employ a zeolite havving a constraint indexfrom 1.0 to 12.0. Constraint Index (CI) values for some typical zeolitesincluding some not within the scope of this invention are:

    ______________________________________                                        CAS                     C.I.                                                  ______________________________________                                        ZSM-5                   8.3                                                   ZSM-11                  8.7                                                   TMA Offretite           3.7                                                   ZSM-12                  2                                                     Beta                    0.6                                                   ZSM-4 (Omega)           0.5                                                   H-Zeolon                0.5                                                   REY                     0.4                                                   Amorphous                                                                      Silica-alumina         0.6                                                   Erionite                38                                                    ______________________________________                                    

The above described constraint Index is an important, and even critical,definition of those zeolites which are useful as catalysts components.The very nature of this parameter, however, and the recited technique bywhich it is determined, however, admit of the possibility that a givenzeolite can be tested under somewhat different conditions and therebyhave different constraint indexes. Constrainst Index seems to varysomewhat whith severity of operation (conversion). Therefore, it will beappreciated that it may be possible to so select test conditions toestablish multiple constraint indexes for a particular given zeolitewhich may be both inside and outside the above defined range of 1 to 12.

Thus, it should be understood that the parameter and property, "theConstraint Index," as used in this invention, is an inclusive ratherthan an exclusive value. That is, a zeolite, if tested by anycombination of conditions within the limits set forth herein above andfound to have a constraint index of 1 to 12, is included in the instantcatalyst definition regardless that the same identical zeolite testedunder other conditions may give a constraint index value outside of 1 to12.

The class of zeolites defined herein is exemplified by ZSM-5, ZSM-11,ZSM-12, ZSM-21, and other similar materials. Recently issued U.S. Pat.No. 3,702,886 describing and claiming ZSM-5 is incorporated herein byreference.

ZSM-11 is more particularly described in U.S. Pat. No. 3,709,979, theentire contents of which are incorporated herein by reference.

ZSM-12 is more particularly described in U.S. Pat. No. 3,832,449, theentire contents of which are incorporated herein by reference.

U.S. application, Ser. No. 358,192, filed May 7, 1973, and nowabandoned, the entire contents of which are incorporated herein byreference, describes a zeolite composition, and a method of making such,designated as ZSM-21 which is useful in this invention. Recent evidencehas been adduced which suggests that this composition may be composed ofat least two (2) different zeolites, one or both of which are theeffective material insofar as the catalysis of this invention isconcerned. Either or all of these zeolites is considered to be withinthe scope of this invention.

The specific zeolites described, when prepared in the presence oforganic cations, are substantially catalytically inactive, possiblebecause the intracrystalline free space is occupied by organic cationsfrom the forming solution. They may be activated by heating in an inertatmosphere at 1000°F for 1 hour, for example, followed by base exchangewith ammonium salts followed by calcination at 1000°F in air. Thepresence of organic cations in the forming solution may not beabsolutely essential to the formation of this special type zeolite;however, the presence of these cations does appear to favor itsformation. More generally, it is desirable to activate this type zeoliteby base exchange with ammonium salts followed by calcination in air atabout 1000°F for from about 15 minutes to about 24 hours.

Natural zeolites may sometimes be converted to this type zeolite byvarious activation procedures and other treatments such as baseexchange, steaming, alumina extraction and calcination, alone or incombinations. Natural minerals which may be so treated includeferrierite, brewsterite, stilbite, dachiardite, epistilbite, heulanditeand clinoptilolite. The preferred crystalline aluminosilicates areZSM-5, ZSM-11, ZSM-12, and ZSM-21, with ZSM-5 particularly preferred.

The zeolites used as catalyst components in this invention may be in thehydrogen form or they may be base exchanged or impregnated to containammonium or a metal cation complement. The metal cations that may bepresent include any of the cations of the metals of Groups I throughVIII of the periodic table. However, in the case of Group IA metals, thecation content should in no case be so large as to substantiallyeliminate the activity of the zeolite for the catalysis being employedin the instant invention. For example, a completely sodium exchangedH-ZSM-5 appears to be large inactive.

In a preferred aspect of this invention, the zeolites useful herein areselected as those having a crystal framework density, in the dryhydrogen form, of not substantially below about 1.6 grams per cubiccentimeter. It has been found that zeolites which satisfy all three ofthe criteria are most desired. Therefore, the preferred zeolites arethose comprising zeolites having a constraint index as defined above ofabout 1 to 12, a silica to alumina ratio of at least about 12 and adried crystal density in the hydrogen form of not substantially lessthan about 1.6 grams per cubic centimeter. The dry density for knownstructures may be calculated from the number of silicon plus aluminumatoms per 1000 cubic Angstroms, as given, e.g., on page 19 of thearticle on Zeolite Structure by W. M. Meier. This paper, the entirecontents of which are incorporated herein by reference, is included in"Proceedings of the Conference on Molecular Sieves, London, April,1967," published by the Society of Chemical Industry, London, 1968. Whenthe crystal structure is unknown, the crystal framework density may bedetermined by classical pyknometer techniques. For example, it may bedetermined by immersing the dry hydrogen form of the zeolite in anorganic solvent which is not sorbed by the crystal. It is possible thatthe unusual sustained activity and stability of this class of zeolitesis associated with its high crystal anionic framework density of notless than about 1.6 grams per cubic centimeter. This high density ofcourse must be associated with a relatively small amount of free spacewithin the crystal, which might be expected to result in more stablestructures. This free space, however, seems to be important as the locusof catalytic activity.

Crystal framework densities of some typical zeolites including somewhich are not within the purview of this invention are:

    ______________________________________                                                        Void          Framework                                       Zeolite         Volume        Density                                         ______________________________________                                        Ferrierite     0.28    cc/cc      1.76 g/cc                                   Mordenite      .28                1.7                                         ZSM-5,-11      .29                1.79                                        Dachiardite    .32                1.72                                        L              .32                1.61                                        Clinoptilolite .34                1.71                                        Laumontite     .34                1.77                                        ZSM-4 (Omega)  .38                1.65                                        Heulandite     .39                1.69                                        P              .41                1.57                                        Offretite      .40                1.55                                        Levynite       .40                1.54                                        Erionite       .35                1.51                                        Gmelinite      .44                1.46                                        Chabazite      .47                1.45                                        A              .5                 1.3                                         Y              .48                1.27                                        ______________________________________                                    

In the process of this invention, the feed consisting essentially of oneor more of the lower alcohols or ethers derived therefrom is contactedwith the above described catalyst at a temperature of about 250°c toabout 700°C, and preferably about 350°C to 500°C; a contact timeequivalent to or the same as a weight hourly space velocity (WHSV) ofabout 0.5 to 50, preferably about 1.0 to 10.0, it being understood thatWHSV signifies pounds of feed per pound of catalyst per hour; and at anabsolute pressure of about 0.2 to 30 atmospheres. The catalyst may be inthe form of fixed bed, fixed fluid bed, or it may be of the transportbed type.

The product stream in the process of this invention contains steam and ahydrocarbon mixture particularly rich in the light olefins, ethylene andpropylene, and aromatic hydrocarbons.

Generally, a major fraction of the total olefins, calculated on a molbasis, is ethylene plus propylene; and a major fraction of these twoolefins is ethylene. The predominant aromatic hydrocarbons aremonocyclic hydrocarbons such as benzene, toluene and xylene. Thus, thepredominant hydrocarbons are all valuable petrochemicals. The steam andhydrocarbons are separated from one another by methods well known in theart. The particular proportions of olefins and aromatic hydrocarbonsthat are produced may be varied by varying the ratio of antimony oxideto crystalline aluminosilicate, higher antimony oxide contents favoringolefin formation. The proportions also may be varied by selectingreaction conditions within the purview specified above, olefins beingfavored by lower temperatures and in general by less severe convversionconditions. Thus, it is a feature of this invention that the product mixcan be easily varied to suit changes of demand.

Catalyst deactivated by coke deposited during the process may bereactivated by calcining in air, for example by calcining at 500°C forabout 20 hours. Operation of the process of this invention in thepresence of added hydrogen may sometimes retard aging.

It is not fully understood why the composite catalyst of this inventionproduces such a desirable spectrum of products. Nonetheless, theconversion of a single carbon feed, such as methanol, or ite ether, withsuch high selectivity to two and three carbon olefins, particularlyethylene, and conjunctly to monocyclic aromatics, is surprising.

The following examples illustrate the practice of this invention withoutbeing limiting on the scope thereof. Parts and percentages are by weightunless expressly stated to be on some other basis.

EXAMPLES EXAMPLE 1

6.5 grams of antimony trimethoxide Sb(CH₃ O)₃ dissolved in 75 cc ofpara-xylene was refluxed with 10 grams of H-ZSM-5 for 16 hours. Themixture was cooled, filtered, and the filter cake washed with 100 cc oftoluene, then 100 cc of methanol, than 100 cc of pentane, after which itwas dried in air. The solids were then vacuum dried at 115°C for 3hours, and formed into pellets without binder. The pellets were thencalcined in air at 300°C for 1 hour. The catalyst contained 24% antimonyas Sb₂ O₃.

EXAMPLE 2

5.0 grams of the catalyst prepared in Example 1 was placed in acatalytic reactor. It was heated to 400°C and 13.2 cc of methanol waspassed over it in 1 hour. Recovered products consisted of 5.9 gramsaqueous liquid, 1.2 grams organic liquid, 1.4 grams liquifiedhydrocarbon gas and 1880 cc of dry gas (hydrogen, methane, ethane andcarbon oxides), accounting for 96 weight percent of the alcohol charged.

A detailed analysis of the recovered product showed that substantiallyall of the methanol charged was converted to hydrocarbon. About 23% ofthe hydrocarbon product consisted of mononuclear aromatics, mostlyxylenes; about 25% was ethylene and about 18% propylene.

EXAMPLES 3-8

13.4 cc per hour of methanol was passed over 4.4 grams of a freshportion of the same catalyst used in Example 2 in a series ofexperiments at different temperatures from 300°C to 500°C. The productswere analyzed with the results shown in Table 1, under Examples 3-7,inclusive. The catalyst, used in Example 7 at 500°C was found to bepartially deactivated. It was calcined in air at 500°C for 18 hours,after which it was used to convert methanol. The results are shown inTable 1 under Example 8.

                                      TABLE 1                                     __________________________________________________________________________    Example                                                                       Number 3    4     5    6    7    8                                            __________________________________________________________________________    Temp. °C.                                                                     300  350   400  450  500  500                                          Aliphatic                                                                     Wt. % (1)                                                                     H.sub.2                                                                              .05  .34   .81  2.55 2.76 2.39                                         CO     .86  1.70  1.86 12.01                                                                              19.78                                                                              17.44                                        CO.sub.2                                                                             .20  .75   .78  6.45 9.11 6.09                                         CH.sub.4                                                                             .58  1.07  2.93 14.59                                                                              44.71                                                                              24.49                                        C.sub.2 H.sub.6                                                                      .23  .44   .78  .98  1.38 .83                                          C.sub.2 H.sub.4                                                                      35.90                                                                              27.05 24.15                                                                              18.83                                                                              10.12                                                                              11.72                                        C.sub.3 H.sub.8                                                                      4.55 3.32  3.07 .96  .25  .38                                          C.sub.3 H.sub.6                                                                      36.92                                                                              29.79 20.43                                                                              12.61                                                                              6.31 5.99                                         C.sub.4 H.sub.10                                                                     4.24 2.11  2.24 .60  .21  .34                                          C.sub.4 H.sub.8                                                                      13.55                                                                              10.18 9.59 5.32 4.03 2.42                                         C.sub.5                                                                              2.92 3.21  4.49 2.94 1.32 2.53                                         C.sub.6                                                                              0    1.14  3.56 1.38 0    .99                                          C.sub.7.sub.+                                                                        0    4.24  3.89 1.13 0    .71                                          Aromatic                                                                      Wt. % (1)                                                                     Benzene                                                                              0    .37   .63  .43  0    .58                                          Toluene                                                                              0    1.77  2.20 2.03 0    3.15                                         Xylenes                                                                              0    8.61  12.81                                                                              10.06                                                                              0    11.31                                        ArC.sub.9                                                                            0    2.50  3.77 4.32 0    4.73                                         ArC.sub.10.sub.+                                                                     0    1.41  2.00 2.83 0    3.91                                                Total Product Yield                                                           7.47 19.17 39.92                                                                              38.45                                                                              7.56 41.41                                        MeOMe  50.07                                                                              32.30 3.56 8.17 44.83                                                                              5.65                                         MeOH   13.90                                                                              13.84 6.33 9.09 22.60                                                                              8.46                                         H.sub.2 O                                                                            28.56                                                                              34.70 50.19                                                                              44.29                                                                              25.01                                                                              44.48                                               Conversion %                                                                  86.12                                                                              86.16 93.67                                                                              90.91                                                                              77.40                                                                              91.54                                               Material Bal. %                                                               99.49                                                                              100.48                                                                              96.32                                                                              94.42                                                                              94.44                                                                              96.41                                        __________________________________________________________________________      (1) Based on hydrocarbon portion only (excludes MeOh, Me.sub.2 O, H.sub.     O).                                                                      

What is claimed is:
 1. A process for producing hydrocarbons whichcomprises: contacting, under conversion conditions, a feed consistingessentially of one or more lower monohydric alcohol having up to fourcarbon atoms, the ethers derived therefrom, or mixtures of said alcoholsand ethers, with a catalyst comprising an intimate admixture of an oxideof antimony and a crystalline aluminosilicate zeolite having a silica toalumina ratio of at least about 12 and a constraint index from 1 to 12,said antimony oxide constituting at least 1% by weight of saidadmixture, whereby is formed a mixture comprising light olefins,monocyclic aromatic hydrocarbons, and water; and, recovering saidhydrocarbons.
 2. The process of claim 1 wherein said conversionconditions include a space velocity of about 0.5 to 50 WHSV, atemperature of about 300°C to about 550°C, and a pressure of about 0.2to 30 atmospheres.
 3. The process of claim 2 wherein said feed ismethanol, dimethyl ether or mixtures thereof.
 4. The process of claim 1wherein said crystalline aluminosilicate zeolite is HZSM-5.
 5. Theprocess of claim 1 wherein the ratio of antimony oxide to crystallinealuminosilicate zeolite is from about 0.01 to about 0.50.
 6. The processof claim 1 wherein the ratio of antimony oxide to crystallinealuminosilicate zeolite is from about 0.03 to 0.30.
 7. The process ofclaim 6 wherein said feed consists essentially of methanol, dimethylether or mixtures thereof.
 8. A novel catalyst composition useful forconverting lower alcohols to petrochemical-type hydrocarbons, whichcomprises a composite of antimony oxide and a crystallinealuminosilicate zeolite having a silica to alumina ratio of at leastabout 12, a constraint index of from 1 to 12, and a dried crystaldensity in the hydrogen form not less than about 1.6 grams per cubiccentimeter, wherein said composite contains at least 1% by weight ofantimony oxide.
 9. A novel catalyst composition as described in claim 8,wherein said zeolite is HZSM-5 and wherein the ratio of said antimonyoxide to crystalline aluminosilicate is from about 0.01 to 0.50.
 10. Amethod for preparing a catalytic composition useful in the conversion ofalcohols to hydrocarbon mixtures, which comprises: heating together asolution of antimony trimethoxide and a crystalline aluminosilicatezeolite for a time sufficient to form an intimate mixture of saidzeolite and an insoluble antimony compound; recovering said intimatemixture; and calcining said recovered mixture in air.
 11. The method ofclaim 10 wherein said crystalline aluminosilicate zeolite is H-ZSM-5.